It is a well known fact that most of the time, threads in a ring-spinning machine break between the drawing device and the thread guide in the so-called spinning zone, where the slubbing coming out of the drawing device has not hardened so much that it can withstand every thread tension tip. In addition, the conventional thread guide—the so-called thread-guiding eyelet—allows only the partial twisting propagation of the traveler device in the spinning zone.
For several decades, textile engineers have made many suggestions for solving this problem: For example, it has been suggested to place so-called crowns on the ring spindle in order to make the twisting that originates in the traveler circling around the ring and moving towards the spinning triangle more effective and to achieve a better hardening of the slubbing coming out of the drawing frame in the critical zone (DE 1 116 584). In these spindle attachments, the thread places itself on the teeth of the crown and is taken along with them, but the yarn on the crown must make the same backward movement as the traveler on the spinning ring, which—correspondingly to the winding up motion and the winding up speed—remains back in the circumferential speed of the spindle. The thread is kept back in the crown tooth until the tension becomes so great that the thread jumps to the next tooth. Thus, the thread jumps backwards from tooth to tooth as the traveler remains behind. The resulting friction leads to undesired yarn damage and napping. Furthermore, each jump causes a tension jolt, which leads to an uneven twisting and integration of the fibers as they emerge from the drawing frame. Therefore, the aim is to use the fewest teeth possible. In the so-called spindle finger that is attached to the ring spindle, for example, there is only one tooth left. The smooth spindle finger causes less napping on the yarn, but it works virtually like a one-tooth crown through which the yarn is taken. This means that the jump is considerably greater, almost one turn, and this spindle finger solution causes considerable thread jolts, which in turn lead to thread breaks and an uneven yarn.
DE 196 29 787 A1 describes a rotating thread guide that has been placed as twisting apparatus between the usual thread guide above the spindle and the ring traveler directly above the ring spindle. Here, a turning body is taken from the spindle by means of a magnetic coupling.
The fiber composite is centrically introduced and led sideways out of the turning body, from which the fiber composite extends towards the ring traveler in one balloon. Alternatively, the turning body is supposed to have a helically-shaped channel and move slower or faster than the spindle independently from it. As a result of this, less false twist can be temporarily superimposed on the fiber composite.
The thread guide connected upstream, however, interferes with the generated twisting movement as it propagates towards the drawing frame. It has not been possible to introduce this known device in practice too because no defined twisting is imparted and the external impulse is too time-consuming.
To avoid these disadvantages, WO 2004/072339 has suggested placing a thread-guiding device with a twisting element at a certain distance above the upper end of the ring spindle and to couple this twisting element with the ring spindle via a magnetic force field. The twisting element has a thread-braking device that consists of a core—extending coaxially towards the twisting axis so the thread running through the thread-guiding device can wind around the core—and a catching edge arranged on the core. This design of the thread-guiding device can catch the thread and make it pass through the twisting element in a defined way so that the thread is imparted with a defined twist in the critical section between thread-guiding device and drawing frame. The winding up movement is done continuously and smoothly. This thread-guiding device has given outstanding results. In the critical section between drawing frame and thread-guiding device more than 100% of the twist is achieved in the thread F′ before the spinning triangle relative to the desired twisting in the finished yarn. A jumping over crown teeth or something similar and the imponderable nature of a twisting caused by friction are no longer needed.
It was thus possible to increase the spinning revolutions significantly. The reduction in size of the spinning triangle and the improved binding of the threads achieved a significant quality improvement of the thread in addition to increased productivity. Even though the balloon diameter was reduced so much that balloon-constricting rings could be largely dispensed with, the higher spinning revolutions achieved with this design led to higher energy requirements. Furthermore, the coupling element placed on the spindle head for taking up the twisting element made the balloon larger and this caused higher balloon resistance and input.
The task of this invention is to lower the energy requirement in a thread-guiding device of this known type so higher production outputs can be achieved economically.